The Study of Osteoporotic Fractures (SOF) is a multi-center longitudinal study in a cohort of 9,704 older women. SOF has comprehensive data about risk factors for osteoporosis and other diseases, along with an archive of serum, buffy coat and urine specimens. Data from SOF have served for: (1) developing osteoporosis guidelines, (2) estimating the cost-effectiveness of screening for osteoporosis, and (3) planning trials of osteoporosis therapies. They propose to renew SOF to sustain this unique resource and to pursue several new hypotheses. Osteoporosis is a chronic disease and prevention of fractures must be considered over the very long-term, not just the 3-5 year duration of most studies in the field. As the study of osteoporosis and aging with the longest (nearly 15 years) follow-up, SOF will provide the foundation for describing ways to identify people at greatest risk of osteoporosis and fractures decades in advance. They envision a new generation of clinical guidelines based on long-term prediction of risk of fractures and disability. Because they have enriched the cohort with African-American women, SOF will also provide unique information on risk factors for osteoporosis and non-spine fractures in older African American women. SOF was the first study to show a link between low BMD and risk of stroke and this has helped to fuel the interest and new investigations about the links between arterial calcification and osteoporosis. If they demonstrate, and can begin to explain, the link between these two diseases, this may lead to screening tools and treatments that simultaneously decrease the risk of both of these disabling conditions. Preliminary results from SOF suggest that impaired sleep may be a major cause of fractures, disability and decline in cognition in older women. If the next phase of SOF confirms these relationships using more objective measures of insomnia and other sleep disorders, then this might change current clinical policies and practices toward more aggressive screening and better coverage for treatment of sleep disorders. Finally, the value of SOF could be magnified by recruiting other scientists to work on SOF data and samples. They propose to make the database easily accessible to investigators outside of SOF and assist them in making productive use of a database that represents one of the most comprehensive prospective sources of information about the health of older women.